Unmanned conveying apparatus

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2021-191464, filed on Nov. 25, 2021, and the entire contents of which are incorporated herein by reference.

The present invention relates to an unmanned conveying apparatus that is loaded with a load on a loading section supported by a base section and conveys the load to a designated point.

In a manufacturing site or the like, an unmanned conveying apparatus is used to convey components and the like between processes in an unmanned manner and carrying the components and the like into a warehouse. In the manufacturing site, since a layout change due to a process change is frequently performed and various manufacturing apparatuses are disposed, a conveyance line is narrow and a route tends to be complicated. Therefore, an unmanned conveying apparatus, in particular, an AMR (Autonomous Mobile Robot) that can turn in a small circle and is easily introduced into an existing factory is attracting attention.

An apparatus explained below has been proposed as an unmanned conveying apparatus.

The apparatus includes a truck main body including a traveling driving section, a placing table on which a load is placed, a rotating device that rotates the placing table centering on an axis in an up-down direction, and a controller that controls a carrier. The placing table and the rotating device are supported to be capable of rising and falling with respect to the truck main body. Two driving wheels arranged on the left and the right are disposed in the center of the truck main body. Driven wheels (caster wheels) are disposed in the front and the rear of the two driving wheels. The driven wheels in the front and the rear are, for example, respectively disposed one by one on the left and the right. Positional deviation of the load placed on the placing table is detected by a camera attached to the truck main body upward and a movement of the carrier is restricted (PTL 1: JP-A-2021-17309).

However, the unmanned conveying apparatus is disposed in various environments. A traveling surface is not always a flat surface and is sometimes an incline surface or an uneven surface. For example, if the traveling surface is inclined, the front and rear driven wheels are grounded but the driving wheels in the center rise and the unmanned conveying apparatus is likely to be unable to travel when entering the traveling surface. Accordingly, a wheel-type traveling apparatus explained below has been proposed. A first wheel supporting section that supports both of driving wheels and auxiliary wheels and a second wheel supporting section that supports only the auxiliary wheels are rotatably coupled in a vertical direction. The driving wheels and the auxiliary wheels are disposed in positions where the driving wheels and the auxiliary wheels can self-stand. Only one or a plurality of auxiliary wheels arranged in a lateral direction are disposed to be independently unable to self-stand on the second wheel supporting section. A load is placed on and a weight is applied to the second wheel supporting section. A coupling section of the first wheel supporting section and the second wheel supporting section is set in a middle position between the driving wheels and the auxiliary wheels on the first wheel supporting section. Therefore, irrespective of whichever of the first and second wheel supporting sections a weight is applied to, a pressing force to a traveling road is applied to both of the driving wheels and the auxiliary wheels in the first wheel supporting section. Consequently, irrespective of whichever of the front and the rear of the first wheel supporting section a bent section of an inclined surface is disposed in, it is guaranteed that the driving wheels are grounded at a predetermined pressure. Therefore, an untravellable state and a tumble due to a steep slope climb are prevented (PTL 2: JP-A-2005-313720).

However, in the unmanned conveying apparatus of PTL 1 explained above, the placing table and the rotating device are supported by the truck main body to be capable of rising and falling. In the unmanned conveying apparatus of PTL 2, the first wheel supporting section that supports both of the driving wheels and the auxiliary wheels and the second wheel supporting section that supports only the auxiliary wheels are coupled in the vertical direction to be capable of rotating. Therefore, both of the unmanned conveying apparatus have large vehicle heights. Loads placed on the placing table and the second wheel supporting section are likely to be collapsed when the unmanned conveying apparatuses travel on a slope or an uneven surface. In the unmanned conveying apparatus of PTL 2, the first wheel supporting section and the second wheel supporting section are rotatably coupled in the height direction. Therefore, a placing space for a load is limited.

The present invention has been devised to solve these problems, and an object of the present invention is to provide an unmanned conveying apparatus that achieves low flooring of a vehicle body and enlarges a placing space for a load and is capable of stably traveling without driving wheels rising even if an inclination or unevenness is present on a traveling surface.

The present invention has the following configuration in order to achieve the object.

An unmanned conveying apparatus that is loaded with a load on a loading section supported by a base section and travels and conveys the load to a designated point, the unmanned conveying apparatus including: a pair of driving wheels driven to rotate by driving motors; a pair of first auxiliary wheels respectively turnably supported by a first wheel supporting section provided on one end side of the base section centering on the driving wheels; and a pair of second auxiliary wheels respectively turnably supported by a second wheel supporting section provided on another end side of the base section, wherein the first auxiliary wheels and the driving wheels are respectively supported by the first wheel supporting section, and the first wheel supporting section is swingably supported by the base section between the loading section and the base section.

In this way, the first wheel supporting section that supports the first auxiliary wheels and the driving wheels are swingably supported by the base section. Therefore, the unmanned conveying apparatus is capable of stably travel without the driving wheels rising even if an inclination or unevenness is present on a traveling surface. Since the first wheel supporting section is disposed between the loading section and the base section, it is possible to achieve low flooring of a vehicle body. It is possible to widely use the loading section supported by the base section for load loading.

It is preferable that the first auxiliary wheels are turnably supported on one end side of the first wheel supporting section, the driving wheels are rotatably supported on another end side of the first wheel supporting section, and the first wheel supporting section is swingably axially supported, via a swinging shaft, by a swing supporting section provided on the base section.

Consequently, even if an inclination or unevenness is present on the traveling surface, the first wheel supporting section swings via the swinging shaft while the driving wheels are kept grounded and the first auxiliary wheels follow the traveling surface. Therefore, the unmanned conveying apparatus is capable of stably traveling without the driving wheels becoming incapable of traveling.

It is preferable that the swinging shaft is provided between the first wheel supporting section and the base section.

Consequently, the first wheel supporting section swings using a space between the base section and the loading section. Therefore, it is possible to suppress a vehicle height and achieve low flooring.

The first wheel supporting section may be swingably supported by the base section such that a distance from a swinging shaft position to a driving wheel side end position is longer than a distance from the swinging shaft position to a first auxiliary wheel side end position on the first wheel supporting section.

Consequently, a weight is always more easily applied to the driving wheel side compared with the first auxiliary wheel side. Therefore, it is possible to maintain a grounded state of the driving wheels and realize stable traveling.

An imaging camera and a laser distance sensor may be provided in the base section, and the unmanned conveying apparatus may autonomously travel while simultaneously performing environmental map creation and own-position estimation with inputs from the imaging camera and the laser distance sensor.

In this case as well, it is possible to apply an SLAM (Simultaneous Localization and Mapping: simultaneous execution of own-position estimation and environmental map creation) technique and improve reliability of an autonomous conveying operation while securing a wide space of the loading section on which a load is loaded.

It is possible to provide an unmanned conveying apparatus that achieves low flooring of a vehicle body and enlarges a placing space for a load and is capable of stably traveling without driving wheels rising even if an inclination or unevenness is present on a traveling surface.

A schematic configuration of an unmanned conveying apparatus according to the present invention is explained below with reference to. The unmanned conveying apparatus is a trackless vehicle that is loaded with a load on a loading section by an operator or automatically, travels to a designated place, and is unloaded with the load by the operator or automatically. The unmanned conveying apparatus is equipped with SLAM (Simultaneous Localization and Mapping: simultaneous execution of own-position estimation and environmental map creation). The SLAM is roughly classified into three types according to differences of input sensors. There are LiDER SLAM in which an LiDAR (a laser distance sensor) is used as an input, Visual SLAM in which an imaging camera is used, and Depth SLAM in which distance measurement information from a ToF sensor or the like is used. As explained below, the unmanned conveying apparatus in this embodiment improves reliability of an autonomous conveying operation by using coordinate information by the LiDAR (the laser distance sensor) and image information of the imaging camera in combination.

First, as shown in, in an unmanned conveying apparatus, a loading sectionis supported by a base sectionvia columns. On both the left and right sides of the base section, a pair of driving wheelsis provided in the center. Six wheels in total including a pair of first auxiliary wheels(front wheels) and a pair of second auxiliary wheels(rear wheel) are provided in the front and the rear of the pair of driving wheels(see).

As shown in, the pair of driving wheelsis respectively driven to rotate by driving motors,. In the base section, centering on the pair of driving wheels, a pair of auxiliary wheelsis respectively provided on one end side (a front side) of the base sectionand a pair of second auxiliary wheelsis respectively provided on the other end side (a rear side) of the base section.

As shown in, the first auxiliary wheel(the front wheel) is turnably supported by a casteron one end side of an elongated plate-like first wheel supporting section. The driving motoris integrally assembled to a motor attachment plateon the other end side of the first wheel supporting section. A driving shaftof the driving motoris extended further to an outer side than the motor attachment plate. The driving wheelis fit in the driving shaft

The first wheel supporting sectionis swingably supported, via a swinging shaft, by a swing supporting sectionprovided in the base sectionbetween the loading sectionand the base section. The swing supporting sectionis protrudingly provided in the base section. A shaft holeis bored in the swing supporting section. A shaft supporting plateis protrudingly provided on an opposed surface of the first wheel supporting sectionopposed to the base section. The swinging shaftis protrudingly provided in the horizontal outward direction in the shaft supporting plate. The swinging shaftof the first wheel supporting sectionis fit in the shaft holeof the swing supporting section. The first wheel supporting sectionis supported to be capable of swinging centering on the swinging shaft

Traveling operations of the unmanned conveying apparatuscorresponding to traveling surfaces are explained with reference to. Only a configuration of a main part of the unmanned conveying apparatusis shown. It is assumed that the unmanned conveying apparatusis traveling toward the right side in.shows a traveling state of the unmanned conveying apparatusin the case in which a traveling surface is a flat land. The first wheel supporting sectionand the base sectionare parallel. All the wheels are grounded on the traveling surface.

shows a traveling state of the unmanned conveying apparatusin the case in which a traveling surface is an uphill road. The first wheel supporting sectionswings upward to the right centering on the swinging shaftwith respect to the base sectionand all the wheels are grounded on the traveling surface.shows a traveling state of the unmanned traveling apparatusin the case in which a traveling surface is a downhill road. The first wheel supporting sectionswings downward to the right centering on the swinging shaftwith respect to the base sectionand all the wheels are grounded on the traveling surface.

As it is seen with reference to, the first wheel supporting sectionthat supports the first auxiliary wheelsand the driving wheelsis swingably supported, via the swinging shaft, by the swing supporting sectionprovided in the base section. Therefore, since the first wheel supporting sectionswings on the base sectionand the first auxiliary wheelsfollow a traveling surface even if an inclination or unevenness is present on the traveling surface, the driving wheelsare kept grounded and the unmanned conveying apparatusdoes not become incapable of traveling and is capable of smoothly climbing over a step section and an inclined surface and stably travel. Since the first wheel supporting sectionis disposed between the loading sectionand the base section, it is possible to achieve low flooring of a vehicle body. It is possible to widely use the loading sectionsupported by the base sectionfor load loading.

Since the swinging shaftis provided between the first wheel supporting sectionand the base section, the first wheel supporting sectionswings using a space between the base sectionand the loading section. Therefore, it is possible to suppress a vehicle height and achieve low flooring.

The first wheel supporting sectionis supported with respect to the base sectionsuch that a distance Lfrom the position of the swinging shaftto the end position on the driving wheelside is longer than a distance Lfrom the position of the swinging shaftto the end position on the first auxiliary wheelside on the first wheel supporting section(L<L). Consequently, since a large weight is always easily applied to the driving wheelside compared with the first auxiliary wheelside, it is easy to maintain a grounded state of the driving wheels.

The second auxiliary wheelsare respectively turnably supported by castersin second wheel supporting sectionsprovided on the left and the right of the base section. Both of the first auxiliary wheelsand the second auxiliary wheelsare driven wheels attached with casters and are configured to turn according to a difference between rotating speeds of the left and right driving wheelsand turn in a small circle. In this embodiment, a minimum rotation diameter is 800 mm and a 360° turn is possible.

As shown in, in the base section, cutoutsand bored holesare provided in positions where the driving wheels, the first auxiliary wheels(the front wheels), and the second auxiliary wheels(the rear wheels) are provided and low flooring of the unmanned conveying apparatusis achieved. As shown in, a load is loaded, by the operator or automatically, on a flat surface of the loading sectionsupported by the base section.

As shown in, the pair of driving wheelsis coupled to the driving shaftsof the driving motors,and driven to rotate. As explained below, motor rotation sensors,are respectively provided in the driving motors,. When movement accuracy is further improved, rotary encoders (not shown) may be provided in the driving motors,(see). Rotating speeds and rotating positions of the left and right driving wheelsare transmitted to a control unit explained below by rotation signals of the motors.

An imaging camera(a camera for grasping environment) is provided in the front of the base section. The imaging cameraimages a peripheral environment and reads a two-dimensional code and the like. The imaging cameradetects upper and lower obstacles that a laser distance sensorexplained below cannot capture. As a type of the imaging camera, a single lens camera (a wide angle camera, a fish-eye camera, or an omnidirectional camera), a compound eye camera (a stereo camera or a multicamera), an RGB-D camera (a depth camera or a ToF camera), or the like is used. In this embodiment, the stereo camera is used.

It is preferable that the imaging camerais provided in a height position in a projection surface of the loading sectionand between the base sectionand the loading section. Consequently, a space above the loading sectioncan be widely used as a space for loading a load, contributing to low flooring of the unmanned conveying apparatus.

A laser distance sensor(LiDAR) is provided below the imaging camera. The laser distance sensormeasures a distance to a target object with a difference in a time until reflected light of laser light irradiated from a laser scanner is received. The laser distance sensorirradiates laser light to acquire point group data of 3D (x, y, and z coordinates) and creates an environmental map. The created environmental map is stored in a data storing unitof a control unitdescribed below and used to estimate a position and detect an obstacle when the unmanned conveying apparatusconveys a load.

As shown in, the base sectionincludes the control unitthat calculates, with a predetermined algorithm, a route to a point designated based on map data and sends a driving command, and a motor driving device(a driving unit) that controls the driving of the pair of driving motors,up to the designated point while simultaneously performing own-position estimation and environmental map creation with input data from the imaging cameraand the laser distance sensor(see).

In the base section, a terminal boxincluding a cable terminal for charging, a battery, an LED light, and the like are provided.

A control system of the unmanned conveying apparatusis explained with reference to a block configuration diagram of. The control unitincludes a microcomputer, a memory, a data storing unit, a communication circuit, and a position estimating device. The microcomputer, the memory, the data storing unit, the communication circuit, and the position estimating deviceare connected by a communication busand are capable of exchanging data with one another. The imaging cameraand the laser distance sensorare connected to the communication busvia a communication interface (not shown) and transmit measurement data, which are measurement results, to the microcomputer, the position estimating device, and/or the memory

The microcomputeris a processor or a control circuit (a computer) that performs an arithmetic operation for controlling the operation of the unmanned conveying apparatus. Typically, the microcomputeris a semiconductor integrated circuit. The microcomputertransmits a PWM (Pulse Width Modulation) signal, which is a control signal, to the motor driving deviceto control to drive motor driving circuits,and adjusts voltages applied to the driving motors,. Consequently, each of the pair of driving motors,can be rotated at desired rotating speed. The motor driving circuits,include inverter circuits. Electric currents flowing to the driving motors,are ON/OFF-controlled by the PWM signal transmitted from the microcomputer

Note that, one or more control circuits (for example, microcomputers) that control driving of the left and right driving motors,may be provided. For example, the motor driving devicemay include two microcomputers that respectively control the driving of the driving motors,. The two microcomputers may respectively perform coordinate calculation using encoder information output from the rotation sensors,and estimate a moving distance of the unmanned conveying apparatusfrom an initial position. The two microcomputers may control the motor driving circuits,using the encoder information.

The memoryis a volatile storage device that stores a computer program to be executed by the microcomputer. The memorytemporarily stores input data and can be used as a work area when the microcomputerand the position estimating deviceperform arithmetic operations.

The data storing unitis a nonvolatile semiconductor memory device (a database). Note that the data storing unitmay be a magnetic recording medium represented by a hard disk or an optical recording medium represented by an optical disk. Further, the data storing unitmay include a head device for writing data in and/or reading data from any recording medium and a control device for the head device.

The data storing unitstores an environmental map (map data M) of a moving space in which the unmanned conveying apparatustravels and data of one or a plurality of traveling routes (traveling route data R). The map data M is created when the unmanned conveying apparatustravels in an environmental map creation mode and is stored in the data storing unitat any time. The one or the plurality of traveling route data R are stored in the data storing unitafter the map data M is created. The map data M and the traveling route data R are stored in the same data storing unitin this embodiment but may be stored in different data storing units

The communication circuitis a wireless communication circuit that performs wireless communication conforming to a wireless LAN or a wireless WAN. For example, in the environmental map creation mode for causing the unmanned conveying apparatusto travel and creating an environmental map, the communication circuitperforms the wireless communication conforming to the wireless LAN or the wireless WAN and wirelessly communicates with a terminalin a one to one relation. Note that, for example, a tablet computer is used as the terminal.

The unmanned conveying apparatustravels along a traveling route determined by the traveling route data R while comparing an environmental map (map data M) created in advance and point group data acquired during traveling and output by the laser distance sensorand estimating a position of the unmanned conveying apparatus.

The position estimating deviceperforms creation processing for an environmental map and performs estimation processing for a position of the unmanned conveying apparatusat a load conveyance time. The position estimating devicecreates map data M (point group data of 3D coordinates) of a moving space according to a traveling position of the unmanned conveying apparatusand a scanning result of the laser distance sensor. At the load conveyance time, the position estimating devicereceives 3D coordinate data from the laser distance sensorand reads the map data M stored in the data storing unit. The position estimating deviceestimates a position of the unmanned conveying apparatuson the map data M by performing matching of created local map data (point group data of 3D coordinates) with map data M in a wider range.

In this embodiment, the imaging cameraimages a peripheral environment necessary for performing autonomous traveling and reads a matrix two-dimensional code presented by the operator. Alternatively, an address of a point designated from address information input from the tablet terminalis input to the control unit. The control unitchecks the address of the designated point on the map data M and determines a traveling route to the designated point with a predetermined algorithm. The control unitsends a driving command to the motor driving devicebased on the determined traveling route data R.

Note that, when the imaging cameradetects an obstacle absent in the map data M, the control unitsends a driving stop command to the motor driving deviceand causes the driving motors,to stop the driving. After checking a peripheral situation, the control unitretrieves the traveling route data R to a destination again and determines a traveling route. Consequently, it is possible to improve reliability of an autonomous conveying operation of the unmanned conveying apparatus.